Electrical power transfer system for propeller system

ABSTRACT

A propeller system for an aircraft includes a propeller assembly rotatable about a central axis and a reduction gearbox operably connected to the propeller assembly via a propeller shaft. An electrical power transfer system is positioned such that the gearbox is located axially between the electrical power transfer system and the propeller assembly. The electrical power transfer system includes a slip ring assembly secured to an oil transfer tube extending to the propeller assembly and a brush block interactive with the slip ring assembly to transfer electrical power to a plurality of lead wires extending from the slip ring assembly to the propeller assembly. The brush block is positioned such that brush block tips of the brush block extend toward the slip ring assembly in a substantially radial direction relative to the central axis of the propeller assembly.

BACKGROUND OF THE INVENTION

The subject matter disclosed herein generally relates topropeller-equipped craft. More specifically, the subject disclosurerelates to transfer of electrical power to propeller mounted componentsof the propeller-equipped craft.

A typical rotor or propeller equipped craft is often equipped withcomponents at the rotating rotor such as deicing components, whichrequire electrical power for operation. The deicing components typicallyinclude heating elements embedded into the propeller blades. Wires carryelectrical power to the heating elements when deicing is required. Theheating elements then melt accumulated ice and prevent subsequentformation of ice of the propeller blade surfaces. To transfer electricalpower from the rotationally fixed airframe of the aircraft to therotating propeller, a plate rotating with the rotor is provided and oneor more slip rings are mounted to it. The rotating slip rings interfaceswith a stationary brush block mounted to a front cover of a reductiongear box for the engine driving the propeller. In the aircraft, thebrush block interfaces with a vertical face of the plate containing theslip rings forward of the gearbox. Leadwires from studs attached to theslip rings distribute electrical power to the various rotatingcomponents. Due to the necessary size of the slip rings, the presence offluids and abrasive materials such as sand and dust in the brush blockenvironment, a high level of wear occurs in the brush blocks carbonbrushes and in the slip rings, resulting in excessive amounts ofmaintenance to repair and/or replace the brush block and slip ringcomponents.

BRIEF DESCRIPTION OF THE INVENTION

According to one aspect of the invention, a propeller system for anaircraft includes a propeller assembly rotatable about a central axisand a reduction gearbox operably connected to the propeller assembly viaa propeller shaft. An electrical power transfer system is positionedsuch that the gearbox is located axially between the electrical powertransfer system and the propeller assembly. The electrical powertransfer system includes a slip ring assembly operably connected to anoil transfer tube extending to the propeller assembly and a brush blockinteractive with the slip ring assembly to transfer electrical power toa plurality of lead wires extending from the slip ring assembly to thepropeller assembly. The brush block is positioned such that brush blocktips of the brush block extend toward the slip ring assembly in asubstantially radial direction relative to the central axis

According to another aspect of the invention, a deicing system for apropeller assembly includes a heating element operably connected to apropeller blade of the propeller assembly. A brush block is positionedsuch that a reduction gearbox operably connected to the propellerassembly is located between the brush block and the propeller assembly.A slip ring assembly is operably connected to a rotating element and isinteractive with the brush block to transfer electrical power from thebrush block assembly to the heating element via a plurality of leadwires extending from the slip ring assembly to the heating element. Thebrush block is positioned such that brush block tips of the brush blockextend toward the slip ring assembly in a substantially radial directionrelative to a central axis of the propeller assembly.

These and other advantages and features will become more apparent fromthe following description taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter, which is regarded as the invention, is particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The foregoing and other features, and advantages ofthe invention are apparent from the following detailed description takenin conjunction with the accompanying drawings in which:

FIG. 1 is a schematic view of an embodiment of a propeller system;

FIG. 2 is a cross-sectional view of an embodiment of a slip ringarrangement for a propeller system;

FIG. 3 is a schematic view of another embodiment of a propeller system;and

FIG. 4 is a cross-sectional view of another embodiment of a slip ringarrangement for a propeller system.

The detailed description explains embodiments of the invention, togetherwith advantages and features, by way of example with reference to thedrawings.

DETAILED DESCRIPTION OF THE INVENTION

Shown in FIG. 1 is a schematic view of an embodiment of a propellersystem 10 for an aircraft. The propeller system 10 includes a propellerassembly having a plurality of propeller blades 12 arranged around a hub14. A pitch change actuator 11 is connected to an end of the hub 14. Thepropeller blades 12 include one or more heating elements 30 for deicingof the propeller blades 12. The propeller system 10 is operablyconnected to a reduction gearbox 16 via a propeller shaft 18, which isin turn connected to an engine 20. The reduction gearbox 16 translates arotational speed of the engine 20 into a selected propeller speed,N_(p).

Referring now to FIG. 2, the propeller shaft 18 is supported by shaftbearings 22. Further, one or more tubes, for example, oil transfer tube24 extend along shaft axis 28 toward the propeller blades 12. The oiltransfer tube 24 is supported by the pitch change actuator 11 andinterfaces with a transfer bearing 32 to provide fluid to pitch changeactuator 11 at the hub 14. A brush block 34 is located at an aft side ofthe gearbox 16, in other words the gearbox 16 is located between thepropeller blades 12 and the brush block 34, relative to the shaft axis28. The brush block 34 is at least partially supported by and enclosedin a brush block housing 36. In some embodiments, the brush block 34 issecured to an aft gearbox face 38.

In the embodiment of FIG. 2, the oil transfer tube 24 includes a slipring assembly 40, including a number of slip rings 42 molded into orassembled to a slip ring tube 44. The slip ring tube 44 is concentricwith and is secured to the oil transfer tube 24. In some embodiments,the slip ring assembly 40 includes three slip rings 42. The brush block34 includes a number of brush block tips 46, which interface with theslip rings 42. The brush block 34 receives electrical power from a powersource, for example, generator 48, and transfers the electrical power tothe slip rings 42 via the brush block tips 46. In the embodiment of FIG.2, the brush block tips 46 extend substantially radially relative to theshaft axis 28 toward the slip rings 42. The brush block tips 46 may beshimmed into a selected location relative to the slip rings 42. A numberof lead wires 50 extend from the slip rings 42. The lead wires 50 arerouted through a wire transfer tube 52 installed into the oil transfertube 24. The wire transfer tube 52 rotates about the shaft axis 28 withthe oil transfer tube 24 at N_(p). The wire transfer tube 52 is isolatedfrom oil flow through the oil transfer tube 24 to protect the lead wires50 from damage due to the oil flow.

As shown in FIG. 3, the lead wires 50 exit the wire transfer tube 52 atthe hub 14 and are routed to the heating elements 30 to provide powerthereto for deicing of the propeller blades 12.

In another embodiment, shown in FIG. 4, the slip rings 42 are assembledto, or molded into the slip ring tube 44, which is supported by slipring bearings 60 located at a support shaft 62 extending from the brushblock housing 36 into an interior of the slip ring tube 44. The slipring assembly 40 is operably connected to the oil transfer tube 24 via aslip ring drive tab 64 extending from the slip ring tube 44 to a drivenotch 66 at the oil transfer tube 24. The connection is such thatrotation of the oil transfer tube 24 drives rotation of the slip ringtube 44, and thus the slip rings 42.

Locating the slip ring assembly 40 and brush block 34 at an aft side ofthe gearbox 16 allows for a smaller slip ring plate 54 or utilization ofa slip ring tube 44 secured to the oil transfer tube 24. This results insmaller diameter slip rings 42 and thus lower rotational speed of theslip rings 42 at the slip ring 42/brush block tip 46 interface and lesswear of the slip rings 42 and brush block tips 46. Further, location ofthe brush block 34 and slip rings 42 at an aft side of the gearbox 16shields the brush block 34 and slip rings 42 from contaminants such asdust and sand, reducing erosion wear of the brush block 34 and sliprings 42.

Even though the system described herein is utilized for transfer ofelectrical power to deicing components of the propeller system 10, it isto be appreciated that the electrical power may be provided to therotating portions of the propeller system 10 for other components suchas propeller control systems, propeller dynamic balance systems,instrumentation systems for propeller testing, or the like.

While the invention has been described in detail in connection with onlya limited number of embodiments, it should be readily understood thatthe invention is not limited to such disclosed embodiments. Rather, theinvention can be modified to incorporate any number of variations,alterations, substitutions or equivalent arrangements not heretoforedescribed, but which are commensurate with the spirit and scope of theinvention. Additionally, while the various embodiments of the inventionhave been described, it is to be understood that aspects of theinvention may include only some of the described embodiments.Accordingly, the invention is not to be seen as limited by the foregoingdescription, but is only limited by the scope of the appended claims.

1. A propeller system for an aircraft comprising: a propeller assemblyrotatable about a central axis; a reduction gearbox operably connectedto the propeller assembly via a propeller shaft; and an electrical powertransfer system positioned such that the gearbox is located axiallybetween the electrical power transfer system and the propeller assemblyand including: a slip ring assembly operably connected to an oiltransfer tube extending to the propeller assembly; and a brush blockinteractive with the slip ring assembly to transfer electrical power toa plurality of lead wires extending from the slip ring assembly to thepropeller assembly, the brush block positioned such that brush blocktips of the brush block extend toward the slip ring assembly in asubstantially radial direction relative to the central axis.
 2. Thepropeller system of claim 1, wherein the slip ring assembly comprises: aslip ring tube affixed to the oil transfer tube; and a plurality of sliprings affixed to the slip ring tube.
 3. The propeller system of claim 2,wherein the plurality of slip rings are molded into the slip ring tube.4. The propeller system of claim 1, wherein the slip ring assemblycomprises: a slip ring tube operably connected to the oil transfer tubevia a slip ring drive tab; a slip ring bearing supportive of the slipring tube; and a plurality of slip rings affixed to the slip ring tube.5. The propeller system of claim 1, further comprising a wire routingtube disposed inside of the oil transfer tube, the lead wires routedthrough the wire routing tube.
 6. The propeller system of claim 1,wherein the brush block is secured to an aft face of the gearbox.
 7. Thepropeller system of claim 1, wherein the propeller assembly includes aplurality of propeller blades extending from a propeller hub operablyconnected to the propeller shaft.
 8. A deicing system for a propellerassembly comprising: a heating element operably connected to a propellerblade of the propeller assembly; a brush block positioned such that areduction gearbox operably connected to the propeller assembly islocated between the brush block and the propeller assembly; a slip ringassembly secured to a rotating element and interactive with the brushblock to transfer electrical power from the brush block assembly to theheating element via a plurality of lead wires extending from the slipring assembly to the heating element, the brush block positioned suchthat brush block tips of the brush block extend toward the slip ringassembly in a substantially radial direction relative to a central axisof the propeller assembly.
 9. The deicing system of claim 8, wherein theslip ring assembly comprises: a slip ring tube affixed to an oiltransfer tube disposed at the central axis of the propeller assembly;and a plurality of slip rings affixed to the slip ring tube.
 10. Thedeicing system of claim 9, wherein the plurality of slip rings aremolded into the slip ring tube.
 11. The deicing system of claim 9,wherein the slip ring assembly comprises: a slip ring tube operablyconnected to an oil transfer tube disposed at a central axis of thepropeller assembly via a slip ring drive tab; a slip ring bearingsupportive of the slip ring tube; and a plurality of slip rings affixedto the slip ring tube.
 12. The deicing system of claim 9, wherein thebrush block is secured to an aft face of the gearbox.